The present invention relates to a cogeneration system and, more particularly, to a cogeneration system in which electric power is generated by a gas turbine generator, and at the same time, exhaust heat of the gas turbine generator is recovered to drive a heat-driven refrigerating machine so as to be used for cooling intake air of the gas turbine and as a cold source for an air conditioner.
Hitherto, in order to more effectively recover and store exhaust heat energy of a steam turbine generator as a cogeneration system, it is known to provide an absorption refrigerating machine driven by steam discharged from the steam turbine generator and an intake air cooler for cooling intake air for a gas turbine by using chilled water generated by the absorption refrigerating machine in combination with a gas turbine generator for generating electric power by using gas of fuel (liquid or gas fuel), an exhaust gas boiler for generating steam by exhaust gas from the gas turbine generator, a steam turbine generator driven by steam of the exhaust gas boiler, an ammonia absorption refrigerating machine driven by steam discharged from the steam turbine generator and a thermal storage tank housing a freezable thermal storage medium for storing cold of the ammonia absorption refrigerating machine. Such a cogeneration system is disclosed in, for example, JP-A-2001-50012.
In the prior art cogeneration systems, if an output of the gas turbine is increased in response to increment of the electric power load, an exhaust heat from the gas turbine also increases, so that an output of the heat-driven refrigerating machine (ammonia absorption refrigerating machine) which is driven by using the exhaust heat of the gas turbine becomes excessive. On the other hand, when the electric power load decreases or when load of an air conditioner increases, the exhaust heat of the gas turbine relatively decreases since the output of the gas turbine is regulated by the electric power load, so that capacity of the heat-driven refrigerating machine becomes insufficient and cannot meet a load requirement of the air conditioner.
Also, in the ammonia absorption refrigerating machine, if high-temperature exhaust heat is used, pressure in a regenerator increases, so that a double-effect cycle cannot be made up. Therefore, a coefficient of performance of the refrigerating machine cannot be increased. If a water-lithium bromide based absorption refrigerating machine is used, evaporating temperature cannot be made 0xc2x0 C. and lower, so that ice thermal storage cannot be accomplished, and thus the size of the thermal storage tank increases.
Further, if the temperature of the exhaust heat is decreased so as to increase efficiency of the gas turbine, the absorption refrigerating machine cannot be operated, so that cooling operation of the air conditioner cannot be performed.
An objects of the present invention is to solve the above problems, and is to provide a cogeneration system which properly copes with a variation in the electric power load and the load of an air conditioner, dissolves supply-demand unbalance between heat and electric energy, and improves thermal efficiency of the system. The present invention is to solve at least one of the above-described problems.
To achieve the above object, the present invention provides a cogeneration system in which exhaust heat of a gas turbine for driving a generator is recovered and cold is generated by driving a refrigerating machine with the recovered exhaust heat, and the cold is used for cooling intake air for the gas turbine and as a cold source for an air conditioner, wherein the system comprises a thermal storage tank for storing the cold generated by the refrigerating machine and electric energy storage equipment for storing electric energy generated by the generator; and cooling of the intake air for the gas turbine, the thermal storage, and the electric energy storage are controlled in relation to the load of the air conditioner and the electric power load of the generator.
Thereupon, in the case where the electric power load increases and thus the output of gas turbine must be increased, when the load of the air conditioner is low, the intake air for the gas turbine is cooled by the cold of the refrigerating machine to increase the output of the turbine, and when the exhaust heat is in surplus, the surplus refrigeration capacity of the refrigerating machine can be stored in the thermal storage tank. Accordingly, when the electric power is in surplus, it is possible to store the surplus electric power in the electric energy storage equipment without decreasing the output of the gas turbine, and it is possible to cope with the load of the air conditioner without decrement of the capacity of the refrigerating machine. Thus, it is possible to properly cope with a variation in the electric power load and the load of the air conditioner, to dissolve the supply-demand unbalance between the heat and the electric energy and to improve the thermal efficiency of the system.
Also, the present invention provides a cogeneration system in which a refrigerating machine is driven by using exhaust heat of a gas turbine generator, and cold generated by the refrigerating machine is used for cooling intake air for the gas turbine generator and as a cold source for an air conditioner, wherein the system comprises a thermal storage tank for storing the cold generated by the refrigerating machine and an electric energy storage equipment for storing electric energy generated by the gas turbine generator; the electric power load of the gas turbine generator and the load of the air conditioner are detected; when it is judged that the capacity of the gas turbine generator is insufficient and the capacity of the air conditioner is in surplus, the intake air cooling is performed and the thermal storage and electric energy storage are stopped; when it is judged that the capacity of the air conditioner is insufficient and the capacity of the gas turbine generator is in surplus, the electric energy storage is accomplished and the intake air cooling and thermal storage are stopped; when it is judged that the capacities of both of the air conditioner and the gas turbine generator are in surplus, the thermal storage and electric energy storage are accomplished and the intake air cooling is stopped; and when it is judged that the capacities of both of the air conditioner and the gas turbine generator are insufficient, the thermal storage and electric energy storage are stopped and the intake air cooling is performed by using the stored heat.
Further, in the present invention, it is preferable that heat exchange between chilled water cooled by the refrigerating machine and the intake air for the gas turbine is effected by a water-air heat exchanger.
Further, in the present invention, it is preferable that the chilled water cooled by the refrigerating machine is sprayed to thereby cool the intake air of the gas turbine.
Further, in the present invention, the refrigerating machine is preferably a water-lithium bromide based absorption refrigerating machine. Thereby, a double-effect cycle can be made up, so that the coefficient of performance of the refrigerating machine can be increased.
Further, in the present invention, the refrigerating machine is preferably an adsorption refrigerating machine using an adsorbent which can be regenerated. Thereby, even if the efficiency of the gas turbine is improved and thus the temperature of the exhaust heat is lowered, the refrigerating machine can be operated, so that the cooling operation of the air conditioner can be performed.
Further, in the present invention, it is preferable that the refrigerating machine comprises an absorption refrigerating machine and an adsorption refrigerating machine driven by the exhaust heat which has driven the absorption refrigerating machine.
Further, in the present invention, it is preferable that the thermal storage using the refrigerating machine is accomplished by using a latent thermal storage medium having a melting temperature of 0xc2x0 C. or higher. Thereby, the thermal storage tank can be made small in size.